Current world events highlight the need to protect both military and civilian ships that are situated in a harbor environment. Potential threats may originate at the surface of the water or below the surface of the water. In order to protect against underwater threats, a traditional diver sonar (SOund, NAvigation and Ranging) system may employ arrays of transducer elements on a larger structure to achieve many highly directional narrow beams to cover an angular sector of ocean to detect against relevant objects, e.g. divers and swimmer delivery vehicles, while disregarding irrelevant objects, e.g. fish. A traditional diver sonar system typically looks in a horizontal direction and must have significant transmit power to provide detection in a large volume of water over a range of several hundred yards. Such sonar systems are quite expensive, typically in a price range of $500,000 to $1,000,000 and generate high power levels that may be objectionable for environmental reasons. Moreover, to adequately protect a ship in a harbor, several sonar systems may be needed, thus increasing the complexity and the cost. Because a traditional sonar system is large in size, heavy, and requires motional stability, the traditional sonar system typically lacks mobile agility and is mounted in a fixed location.
Consequently, a method and apparatus that has a reduced cost, that has mobility so that the sonar system may be transported with the ship as the ship changes locations, that can be configured for a desired perimeter typology, and that uses less power while providing a required degree of protection from underwater predators would be beneficial to advancing the art of diver sonar systems.